Whole-body positron emission tomography (PET) imaging has become an important diagnostic tool for accurately determining the status of primary and metastatic cancerous lesions of many organ systems. However, current clinical PET scanners have approached the limit of sensitivity. There is an increasing need to improve the signal-to-noise ratio in PET, which will lead to better lesion detection, shorter imaging time, and/or lower injected dose. The improvement can be obtained by improving the coincidence timing resolution in the detection of the two back-to-back 511 keV photons from the positron annihilation in PET so that time-of-flight information can be incorporated into the image reconstruction. Time-of-flight PET (TOF PET) holds the only known potential for a significant reduction in the noise levels. The goal of this project is to develop a practical detector module with superior timing resolution than currently available, without compromising its efficiency for detecting 511 keV photons for application in TOF PET. Critical improvements in the development of the detector module include an appropriate scintillator material (LSO) for TOF PET, a multi-anode microchannel plate photomultiplier tube (MCP PMT) technology as the photodetector, and one-to-one coupling of an array of scintillator crystals to the multi-anode MCP PMT. Although the new cerium-doped halide scintillator material (LaBr3) with higher light output and slightly faster decay time than LSO might be a better choice of scintillator material to produce better timing resolution in the detector module, it has much lower stopping power and photoelectric fraction than LSO, which degrades the efficiency of the detector module. Furthermore, the detector technology we propose to develop can be applied to other scintillator materials with outstanding potential for TOF PET that are being currently investigated or will be discovered in the future. The feasibility of the proposed detector module will be thoroughly characterized through the phases of design, construction, optimization, and performance evaluation. The contribution of the detector module will also be modeled through computer simulation and validated by the experimental measurement. The resulting detector module is expected to provide the excellent timing properties needed for improving the imaging performance of next generation PET scanners by enabling TOF.